The present invention relates to a data output circuit of a semiconductor memory device, and more particularly, to a data output circuit and method for improving a slew rate of an output data signal in a semiconductor memory device.
In general, a semiconductor memory device can be divided into a core region for processing data and a data input/output region for exchanging data with an external device. The data input/output region has a data input buffer and a data output circuit. The data input buffer buffers data received from the outside before transmitting the data to the core region. The data output circuit receives data from the core region, and pull-up or pull-down drives an output terminal so that the received data can be accurately transmitted to other external devices.
Meanwhile, a slew rate representing a voltage/time slope is an example of a measure that indicates how quickly the voltage level of the output data of the data output circuit changes. The slew rate may be influenced by a semiconductor fabrication process and an operating temperature. The slew rate may also be influenced by the structure of a data output terminal. To be specific, since pads of the data output terminal are disposed adjacent to each other, data outputted through the pad may be affected by data outputted through the other adjacent pads.
What is therefore required is to compensate the slew rate of the data output circuit in consideration of the influence of the adjacent output data that is exerted on the output data because the pads of the data output terminal of the semiconductor memory device are disposed adjacent to each other.